The present invention relates to the field of card-key code responsive locks.
Electronic security locks requiring specific card keys to open them are presently in use in connection with hotels, motels, apartment entrances, industrial areas and the like having doors requiring access by authorized personnel. A "card-key" for actuating the locking devices often comprises a thin plastic card which may be readily stored in the users wallet, typically having iron oxide strips laminated therein, which bear a binary access code for actuating the locks.
Many of these systems are electronic, in that electronic circuits are employed to sense the code formed upon the magnetic strip, amplify the sensed code, and actuate the lock after the proper code is recognized by electronic comparison circuitry. These systems generally require electrical wiring to supply power, and also must be maintained, since electrical circuitry is subjected to malfunctioning. For example, relay contacts become oxidized, and integrated circuits fail, to create such a malfunction.
It is thus an object of the present invention to provide a non-electronic, inexpensive, reliable card-key activated combination lock alternative to electric combination locks, in order to eliminate maintenance problems and downtime due to malfunction, together with the need for electrical wiring which is a nuisance, or other communication links, such as radio channels.
It is a further object of the invention to provide a lock which is primarily mechanical in nature and may be readily actuated by a coded plastic card, not requiring prior art coded "BUMPS" and which is thin enough to be carried in the users wallet, and yet is not permanently magnetized, which would cause the card to mutilate or erase codes formed upon iron oxide strips in other cards carried by the user.
It is a further object of the present invention to provide a locking device which, in contrast with conventional mechanical key locks, do not require tumblers of various sizes, so that the mechanical elements responsive to a given combination code may all be identical to each other, thereby to reduce manufacturing costs, and inventory control problems. In contrast with the prior art, it is desirable to provide a mechanical lock which may be actuated by a thin card key positioned very close to the mechanical latching elements, thereby to minimize the amount of metallic material to be laminated within the plastic card key so that it is thin and flexible. Although the movements of the magnetic portion of the latching elements are quite small in the present invention, due to the closeness of positioning of the card therewith, this movement may be mechanically amplified so as to readily unlatch the latching elements from associated anchor members, thereby to reduce potential manufacturing tolerance problems with respect to the size and placement of the components. Since the card-key code sensing ends of the latching fingers of the present invention are widely separated from the latching ends of the fingers which interact with the anchor members, the proper material may be readily used in connection with the fabrication of each end of the latching element i.e., magnetic material to be positioned at one end of the latching element is generally not suitable for repeated latching with the anchor members due to wear factors.
In U.S. Pat. Nos. RE: 27,753 and 3,271,988 a card key actuates the locking tumblers directly, but requires a substantial movement to unlock the device, to in turn require a substantial magnet or metallic insert within the card, of considerable mass, which is highly unsatisfactory and impracticable since the card key should be thin and light.
U.S. Pat. No. 3,271,953 teaches the use of a card key having a covered metallic sheet punched out in areas that require the magnet lock pins to maintain a separated position when the card key is inserted. This design depends upon the magnetic tumbler pins being held apart from the stationary magnetic pins by means of providing pins polarized with the like poles that repel. When a metallic sheet is placed between these magnetized pins, the repelling force is directed in such a manner as to cause the repelled pin to be attracted to the stationary pin, releasing the sliding lock plate. Thick metallic inserts must be used in the card key designed to alter the repelling forces, because the distance between the locking pins must be great enough to accommodate the locking plates. In contrast, the locks of the present invention do not utilize the principle of dual opposing magnets with like polarities, because the magnet ends of the latch fingers are positioned very close to the card key and can thus be sufficiently attracted to a very thin, low mass, metallic insert within the key to cause the latching finger to be moved through the small distance required to actuate the lock. Additionally, in contrast with prior art teachings, the present invention does not require the physical sliding of a lock plate as in designs of the prior art, and thus a card key may be employed having a relatively slight amount of metallic inserts. Amplification of the relatively small motion of the latching members adjacent the card key results in the latching or unlatching of the lock with ease.